The present invention relates to hybrid heating systems.
Consumer demand for electricity is generally not uniform over the course of a 24-hour period. Electric companies thus find that during peak hours the demand for electricity approaches, or may even exceed, the electricity generating capacity of the company. On the other hand, during hours when the demand for electricity is very low, for example, during part of the night, a significant portion of the electricity generating capacity is not utilized. Electric companies thus search for schemes to induce consumers to transfer some of their electricity consumption from the peak hours of demand to the off-peak hours. For example, many electric companies have instituted a pricing scheme wherein the cost of electricity to the consumer is highest during the period of peak demand and is significantly lower during the hours of low demand. Such a pricing scheme is sometimes known as a “time-of-use” pricing scheme.
Systems that generate hot water and/or steam for bathing, ambient heating and other uses may use electricity or fossil fuels as the energy source. In contrast to heating by electricity, the cost of water heating by fossil fuel burning may remain substantially constant over any 24-hour period. Therefore, in a time-of-use pricing scheme for electricity use, water heating by electricity during peak hours may be more expensive than heating by burning a fossil fuel. On the other hand, water heating by electricity during off-peak hours may be cheaper than heating by burning fossil fuels.
The present inventors have recognized a need for improved hybrid heating systems, and methods of operating such systems.